The Yığma Tepe of Pergamon is one of the largest known burial mounds in the Eastern Mediterranean. Its internal structure, especially the existence and location of burials, remains unknown so far because its height of 32 m and the diameter of 158 m have restricted extensive excavations. To explore the interior of the Yığma Tepe, we applied shear wave reflection profiling and traveltime tomography, locally complemented by electrical resistivity tomography. Shear wave reflection imaging enabled us to identify the layering and localize structures down to the basal surface of the mound with a metre-scale resolution. A grid of crossing SH-wave profiles with 4-m line spacing covered the central mound area. The Yığma Tepe can be subdivided into three stratigraphic layers representing different construction phases, each about 10 m thick. The deepest is a consolidated layer with a locally compacted surface. SH-wave reflection imaging verified the collapsed remains of a tunnel system and a shaft at about 30-m depth that had been dug into the mound at the level of the basal surface at the beginning of the 20th century. The tunnel collapse created a damage zone of decreased S-wave velocity reaching up to the overlying middle layer, in which four seismic objects of interest (SOIs) were detected. The largest of these SOIs is a north–south-oriented structure, about 15 m long and 4 m wide. SH-viscoelastic forward modelling showed that it likely consists of a collapsed walled cavity with a zone of loosened soil above. The third layer covers the underlying two and is enriched with large stone packages as verified by local excavations. We show the capabilities of shear-wave reflection seismic to image small-scale structures under complicated topographic conditions and how characteristics of cavities and volumes of decompacted soil can be evaluated by wavefield modelling.

中文翻译：

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佩加蒙的 Yığma Tepe：从横波反射测深和波场建模的巨大墓葬的内部构造

佩加蒙的耶马丘陵是东地中海已知最大的墓葬群之一。它的内部结构，特别是墓葬的存在和位置，至今仍不为人知，因为它的高度为 32 m，直径为 158 m，限制了广泛的挖掘。为了探索 Yığma Tepe 的内部，我们应用了剪切波反射剖面和走时断层扫描，并在局部辅以电阻率断层扫描。剪切波反射成像使我们能够以米级分辨率识别层状结构并将结构定位到土墩的基底表面。具有 4 米线距的交叉 SH 波剖面网格覆盖了中央土丘区域。Yığma Tepe 可细分为三个地层，代表不同的施工阶段，每层约 10 m 厚。最深的是具有局部压实表面的固结层。SH 波反射成像证实了 20 世纪初在基面水平的土墩中挖入约 30 米深的隧道系统和竖井的倒塌遗迹。隧道坍塌形成了一个 S 波速度降低的破坏区，到达上覆的中间层，在其中检测到了四个感兴趣的地震对象 (SOI)。这些 SOI 中最大的一个是南北向结构，长约 15 m，宽约 4 m。SH-粘弹性正演模型表明，它可能由一个倒塌的有壁空腔组成，上面有一个松散的土壤区域。第三层覆盖了下面的两层，并通过当地挖掘证实了大量的石块。